1. Field of the Invention
The present invention relates to a fastener design, particularly to a screw capable of rapidly drilling and cutting.
2. Description of the Related Art
Referring to FIG. 1, a conventional screw 1 comprises a shank portion 11, a head portion 12 disposed at one end of the shank portion 11, a drilling portion 13 disposed at the other end of the shank portion 11, and a plurality of threaded units 14 spirally disposed around the shank portion 11. Wherein, the drilling portion 13 is formed into a tapered end. Thus, the screw 1 directly enters an object 2 via the tapered drilling portion 13, and the following threaded units 14 continue entering the object 2 so as to achieve a fastening effect.
Afore screw 1 might be smoothly fastened into the object 2 (such as plywood) by means of the drilling portion 13 piercing the object 2. However, in practice, the object 2 is forcedly pierced by the tapered drilling portion 13. Thus, it is difficult to completely sever fibers contained in the object 2. That is to say, the fibers are just simply pushed and thrust by the tapered drilling portion 13, so the screw 1 would be easily impeded by debris resulted from the object 2 in time of drilling. As a result, the debris can not be timely expelled, and the heaped debris incurs an increasing resistance on the screw 1. Thereby, the operation of fastening the screw 1 is influenced and the object 2 may be easily broken.
Referring to FIG. 2, the upright screw 1 in the object 2 might be subject to rustiness since water might pile on the head portion 12. Therefore, in the practical application, the screw 1 is disposed tilting in the object 2. Herein, if the cutting debris can not be timely expelled, the head portion 12 easily bulges out of the object 2 after screwing. Such abnormal operation is unbeneficial for further fastening. Therefore, the screw 1 needs improvements.